Question about my idle

[sbveenker]

So i have a 94 5.8l and when its just sitting there it will idle about 6000-7000 about normal then it will like drop then come back up and continue to do this. It runs fine while your driving and it never drops enough to die. Anyone have ideas

 

[madmax]

So i have a 94 5.8l and when its just sitting there it will idle about 6000-7000 about normal then it will like drop then come back up and continue to do this. It runs fine while your driving and it never drops enough to die. Anyone have ideas

Ill assume you mean 600 to 700 rpms, 6 or 7 thousand would cause valve floating or possibly break a rocker arm.

try cleaning your idle air control valve, also is your ac on when it does this? how big is the drop? does it drop down to 500 or 200? another thing that can cause this is a problem with the EGR valve causing it to smother the engine with too much exhaust.

 

[Burns]

Yea, my engine was hunting for it's idle when I first got it. Carb cleaner and the idle air controller and also cleaned the throttle body. After that, the idle was steady as could be.

 

[sbveenker]

Where is the idle control valve located?

 

[Burns]

Where is the idle control valve located?

On a 5.8, I'm not 100% sure, but it should be like a 5.0. Where your air intake meets your throttle body, on the side of the throttle body should be a cylinder-like device, laying down, about 6-7 inches long. That's your idle air control. It's 2 bolts that hold it to the throttle body, and be careful not to lose the gasket there. It's a tight fit for the bolts.

Hopefully this helps.

 

[miesk5]

yo!

Do you have a check eng. light lit?

if so, should do a scan or self test

Self Test & Connector Location & pics, Bronco & Ford BEST PROCESS WITH DIAGRAMS! Source: by Ryan M

& then post results here;

for now on da IAC:

Sensor, Idle Air Control (IAC) Cleaning in a 93 5.8 Source: by Bobby (blue)

Sensor, Idle Air Control (IAC), Idle or Noise Problems & Troubleshooting Source: by Joe D at carquest.com via web.archive.org

"Ford vehicles with an Idle Air Control

Motor (called IAC) that have idle

problems and sometimes noise concerns

can be diagnosed in the following

manner. For high idle problems, try

unplugging the IAC motor. If the idle

drops, its usually due to an input signal

to the computer which results in the

computer raising the idle speed. If this is

the case, look at all of the computer

inputs to make sure everything is up to

par. If the engine RPM does not drop

when the IAC motor is disconnected,

then either the IAC motor is not

functioning properly, or, there is a

vacuum leak in the engine. Stop the

engine, remove the IAC motor and block

off the passages. Restart the engine to

see if there is any change in engine

RPM. An idle speed higher than base

idle specs indicates a vacuum leak. If the

engine RPM is at base idle specs, then

the IAC motor is bad. Resistance specs

are 7-13 ohms. A good resistance reading

does not necessarily mean that the

IAC motor is good. Occasionally, an

IAC motor will become weak, and will

actually bypass too much air, causing a

high idle condition even though

everything else is operating properly.

Diagnosing an IAC motor and its

circuit is fairly easy. This motor uses a

two wire connector...

read more in his article..

or. other possibilites;

DTC Codes 122 through 125 Troubleshooting & Possible Causes; The Throttle Position Sensor (TPS) is located at the end of the throttle shaft on the throttle body. Using the TPS voltage signal the EEC determines fuel delivery based on throttle position. A bad TPS can be the cause of bad idle, which is caused by the injector pulse fluctuating. Some loss in performance can also be expected.

GL!